Rho-associated protein kinase II (rock II) expression in normal and preeclamptic human placentas

Rho-associated kinases are serine/threonine kinases that have several functions which might contribute to various physiological and pathological states in cells. There are two isoforms of these enzymes known as rho-associated kinase I (rock I, ROKbeta) and II (rock II, ROKalpha). It has been shown that rock II may be a potential mediator of apoptosis. In addition, rocks play a crucial role in the formation of microvilli-like structures. Increased placental apoptosis and microvilli shedding were shown in preeclampsia. We hypothesized that altered rock expression may lead to the pathologies seen in preeclampsia. Therefore in this study we compared placental rock II expression between normotensive and preeclamptic women using immunohistochemistry and Western blot. Immunohistochemistry and Western blot experiments revealed that rock II is mainly localized in syncytiotrophoblast cells of the placental villi and increased in preeclampsia. In addition to 160 kDa rock II molecule we also detected biologically relevant smaller active form of rock II in preeclamptic but not in normal placentas. We suggest that increased rock II expression in preeclamptic placentas may contribute to etiology or pathogenesis of this syndrome. However, it is considered that rock II expression may also increase to compensate for placental functions changing in preeclampsia.